1. Field of the Invention
This invention relates to a head stack assembly used in a disk drive. More particularly, this invention relates to a head stack assembly having an actuator body with multiple slots adjacent to its bore.
2. Description of the Prior Art and Related Information
A huge market exists for disk drives such as hard disk drives for mass-market host computer systems such as servers, desktop computers, and laptop computers. To be competitive in this market, a hard disk drive must be relatively inexpensive, and must accordingly embody a design that is adapted for low-cost mass production. In addition, it must provide substantial capacity, rapid access to data, and reliable performance. Numerous manufacturers compete in this huge market and collectively conduct substantial research and development, at great annual cost, to design and develop innovative hard disk drives to meet increasingly demanding customer requirements.
Each of numerous contemporary mass-market hard disk drive models provides relatively large capacity, often in excess of 40 gigabytes per drive. Nevertheless, there exists substantial competitive pressure to develop mass-market hard disk drives that have even higher capacities and that provide rapid access. Another requirement to be competitive in this market is that the hard disk drive must conform to a selected standard exterior size and shape often referred to as a “form factor.” Generally, capacity is desirably increased without increasing the form factor or the form factor is reduced without decreasing capacity.
Satisfying these competing constraints of low-cost, small size, high capacity, and rapid access requires innovation in each of numerous components and methods of assembly including methods of assembly of various components into certain subassemblies. Typically, the main assemblies of a hard disk drive are a head disk assembly and a printed circuit board assembly.
The head disk assembly includes an enclosure including a base and a cover, at least one disk having at least one recording surface, a spindle motor for causing each disk to rotate, and an actuator arrangement. The printed circuit board assembly includes circuitry for processing signals and controlling operations. Actuator arrangements can be characterized as either linear or rotary; substantially every contemporary cost-competitive small form factor drive employs a rotary actuator arrangement.
The rotary actuator arrangement typically includes a head stack assembly having an actuator body, at least one actuator arm extending from the actuator body, a head gimbal assembly attached to the actuator arm, a coil portion extending from the actuator body in a direction opposite from the actuator arm, and a flex circuit cable assembly.
The head stack assembly may also include a bearing assembly which is fitted around a corresponding rotary actuator shaft on the base allowing the head stack assembly to pivot. The bearing assembly is disposed in a bore of the actuator body, the bore being cylindrically shaped.
The bearing assembly may be attached to the actuator body using various techniques. Some of the techniques require the use of an extra part in addition to the bearing assembly, such as a side screw, a tolerance ring or a C clip retainer ring, which adds to the cost of manufacturing disk drives. Another technique for attaching the bearing assembly to the actuator body is the use of a press fit operation in which the bearing assembly is pressed into the bore thereby resulting in an interference fit between the outer bearing assembly surface and the actuator body's inner cylindrical surface which defines the bore. During such a press fit operation, the outer bearing assembly surface may be deformed which in turn may result in a detenting of the bearing races. The detenting of the bearing races increases friction between the bearing balls and the races.